Portable spot welder



June 11, 1946. R. E. ADAMS PORTABLE SPOT WELDER Filed April 10, 1945 Patented June 11, 1946 PORTABLE SPOT WELDER Robert Earl Adams, Vancouver, to George H. Buckler,

Wash, assignor Portland, Oreg.

Application April 10, 1945, Serial No. 587,563

4 Claims. 1

The present invention relates to welding tools and more particularly to a light weight, portable spot welding gun.

Objects of the invention include providing an eflicient and easily handled welding gun which can be easily and inexpensively made, largely from standard stock material, which will be certain, durable, safe and foolproof in operation, and which will be capable of being used in a wide variety of operations.

A particular field of utility comprises preliminary tacking of more or less light sheet metal or other parts preparatory to finishing the same by arc, spot or other type of welding. The new device is particularly adapted to such use because of the ease with which it can be handled and the versatility with which it accommodates itself to inconvenient and generally hard-to-reach locations.

A principal feature of the device resides in the use of a pistol type of grip and trigger by which the gun may be held in and operated by one hand, leaving the operator's other hand free to hold the work, adjust its position, or for any other purpose.

A related object is to provide means for holding the tool and for putting it into and out of operation, all in one hand of the operator, with the result that the operator's other hand is left free as hereinabove indicated.

Other and further objects and advantages of the invention are contemplated and will be recognized and appreciated by those skilled in the art For the purpose of illustrating the invention, which comprises the essential features of construction pointed out in the appended claims, I have shown in the accompanying drawing and shall describe in the present specification a certain embodiment which is now preferred by me because it has been fully tested and found in actual practice to give satisfactory and reliable results. In this connection it is to be understood that the several parts and elements which make up this embodiment may be variously arranged and organized within the scope of the invention and the claims and that the spirit of the invention is not limited to the precise details of the illustrated embodiment.

In the drawing,

Figure 1 is a bottom plan view of a gun embodying the invention;

Fig. 2 is a side elevational view, reduced scale, of the device shown on a slightly in Fig. 1;

Fig. 3 is a rear end elevational view of the device; and

Fig. 4 is a transverse section taken on the line 4-4 of Fig. 2.

As shown in these figures, a preferred embodiment of the invention comprises a pair of cooperating members which are hinged together and carry electrodes provided with welding tips which are swung toward and away from each other to start and terminate a resistance weld. The device is operated by trigger means which is compressed to bring the tips toward each other and is released to have them automatically'retracted from each other.

The device preferably consists of an upper member l0 and a lower member ll, both made channel shaped out of some relatively hard, rigid dielectric material such, for example, as the can vas Bakelite composition known by the trade name Micarta. The lower member II has attached to it, or made integral with it, a depending pistol type stock I! of a convenient size and shape for gripping in the palm of the operator's hand.

The two members are hinged together by a pin I3 which is set through registering openings in a pair of upper hinge plates ll riveted to the two outer sides of the upper member In and a pair of lower hinge plates l5 riveted to the two outer sides of lower member I I. These plates may be made of mild sheet steel of about one-eighth inch thickness, and of course it is important that the rivets be so arranged that the metallic elements l4, l3, I5 will not short circuit the electrodes which are adapted to be carried by the respective members, as will be hereinafter described.

The pin 13 may be maintained in its hinging position in any convement manner, as by heading one end and drilling the other end portion for a cotter pin or the like.

Each of the members.carries an electrode, such as that shown at IS in the upper member and that shown at I! in the lower member. Each electrode may be made of hard copper or the like, substantially square in cross section, as shown in Figs. 3 and 4, and it is convenient to rivet the electrode l6 directly to the upper member by rivets l8, and to secure the electrode I! in the lower member by means of the same rivets 19 which fasten the lower hinge plate I! in place. If the upper hinge plate It be fixed to the upper member ID by rivets 20 which are spaced from the electrode ii, there is no possibility of short circuiting the two electrodes by the plates II and i5 and any of the rivets.

The two members and their electrodes are kept normally expanded away from each other by a coil compression spring 2 i which is interposed between the two electrodes and separated from each of them by an upper and lower insulating pad or shim 22 and 22.

Each electrode is provided with a front end bore in which a welding tip 24 is clamped, as by means of a nut and bolt combination or the like 25, and the rear end of each electrode is formed to receive a current supplying cable (not shown).

The two members are guided in their swinging movements toward and from each other by a pair of plates 26, conveniently made of the same material as the hinge plates i4 and i5, riveted to the sides of the lower member Ii and having the upper portion of each plate projecting up and I overlapping the sides of the upper member ID, so

as to provide a guideway for the upper member.

To keep the upper member from swinging out beyond the guideway just described, and to pull it down into the guideway when a welding spot is to be made, a pair of links 21 are connected, to each outer side of the upper member ill, by a hinge pin 28 which passes through the upper member, slightly in front of the guide plates 28. These links 21 project below the lower member II and are connected by a hinge pin 29 to the front arm 30 of a lever which is fulcrumed by a pin II mounted in an enlargement in the bottom of each guide plate 28. The rear arm of this lever is turned down and elongated to form a trigger 22 which normally stands away from the stock l2 but is juxtaposed thereto and can be pressed toward the stock when both are held in the operator's hand so that the forward arm 20 will swing down and the links 21 will pull the upper member down toward the lower member.

In this operation the tips 24 are moved toward each other from a limit of separation determined by engagement of the pin 29 with the bottom of the lower member II, and when the approach is sufficiently close an arc is struck between them. This are is extinguished when the trigger is released and the spring 2i moves the members and the tips toward their limit of separation.

The trigger 22 is conveniently made approximatelyas wide as the stock l2 and is curved to conform to the stock and the operator's hand, but is tapered and made thin where it is apertured to pass the pins 29 and II. Bushings iii may be used to center and position the trigger on these pins. It is convenient to make the trigger of bar stock with a plate of sheet metal welded or soldered to the front face of the depending rear arm, as shown in the drawing.

It is believed that it will be evident to those skilled in the art that the preferred construction hereinabove described embodies the principles of the invention as pointed out in the appended claims and achieves the objectsand advantages set forth inthe introduction to this specification.

I claim:

1. A spot welding hand tool comprising a lower member having a depending pistol type stock, an upper member hinged to the lower member near the rear portions of both members, electrodes mounted in both members and adapted to swing relatively to each other in the same plane upon hinging movements of the members, welding tips mounted in the forward portions of the electrodes, a trigger pivoted between its ends to the lower member and having forward and rear arms on opposite sides of the pivot, said rear arm being justaposed to the stock so as in be ipped therewith in the operator's hand, link means connecting the forward arm of the trigger with the upper member between the welding tips and the point at which the members are hinged together, and a spring acting in tension between the member mounted between said point and the tips.

2. A spot welding hand tool comprising a lower member having a depending pistol type stock, an upper member hinged to the lower member near the rear portions of both members, electrodes projecting forwardly and rearwardly from both members and adapted to swing relatively to each other in the same plane upon hinging movements of the members, welding tips mounted in the forward projecting portions of the electrodes, lead connections formed on the rear projecting portions of the electrodes, spring means urging the members apart to separate said tips, a trigger pivoted between its ends to the lower member and having one arm juxtaposed to the stock so as to be gripped therewith in the operators hand, and link means connecting the other arm of the trigger to a point on the upper member between the tip thereof and the hinge between the two members.

3. A spot welding hand tool comprising a lower member having a depending pistol type stock, an upper member hinged to the lower member near the rear portions of both members, electrodes mounted in both members and adapted to swing relatively to each other upon hinging movements of the members, welding tips mounted in the forward portions of the electrodes, spaced guide plates secured to the lower member and project ing at their ends above and below said member, said upper projecting portions forming a guide for constraining the upper member to swing in the plane of the lower member, a trigger having a fulcrum portion between its ends pivoted between the lower projecting portions of the guide plates and having one arm juxtaposed to the stock so as to be gripped therewith in the operators hand, and link means connecting the other arm of the trigger to the upper member.

4. A spot welding hand tool comprising a lower member having a depending pistol type stock, an upper member hinged to the lower member near the rear portions of both members, electrodes mounted in both members and adapted to swing relatively to each other upon hinging movements of the members. welding tips mounted in the forward portions of the electrodes, spring means urging the members apart to separate said tips, spaced guide plates secured to the lower member and projecting at their ends above and below said member, said upper projecting portions forming a guide for constraining the upper member to swing in the plane of the lower member, a trigger having a fulcrum portion between its ends pivoted between the lower projecting portions of the guide plates and having one arm juxtaposed to the stock so as to be gripped therewith in the operator's hand, and link means connecting the other arm of the trigger to the upper member.

ROBERT EARL ADAMS. 

